U.S. patent application number 12/969111 was filed with the patent office on 2011-12-22 for plaque removal and differentiation of tooth and gum.
This patent application is currently assigned to Massachusetts Institute of Technology. Invention is credited to Ian W. Hunter.
Application Number | 20110311939 12/969111 |
Document ID | / |
Family ID | 43760066 |
Filed Date | 2011-12-22 |
United States Patent
Application |
20110311939 |
Kind Code |
A1 |
Hunter; Ian W. |
December 22, 2011 |
Plaque Removal and Differentiation of Tooth and Gum
Abstract
A method of tooth treatment includes sensing a surface condition
of tooth or gum and controlling ejection of a fluid jet against the
tooth based on the sensed condition. The fluid may be a liquid and
may be carried in a self-contained reservoir in a handle of a fluid
ejection device. The liquid can be a cleansing solution and may
contain cleaning particles. The ejection can be controlled to clean
teeth at high pressure and to reduce pressure applied to gum, for
example, to clean plaque. In some embodiments, the method may be
used to remove soft tooth. The method may further include
automatically scanning the fluid jet relative to a handle of an
injection device. In an embodiment, the fluid is ejected by means
of a fluid ejector comprising a stationary magnet assembly
providing a magnetic field and a coil assembly, slidably disposed
with respect to the magnet assembly, the coil assembly driving
ejection of the fluid jet. Sensing the surface condition can
include measuring a response of tissue to a mechanical perturbation
and may include sensing an acoustic signal reflected from tissue.
The mechanical perturbation can include applied force and the
measured response can include deformation of the tissue. The method
may further include mechanically disturbing the tissue with the
fluid jet. A tooth treatment device includes a fluid ejector that
ejects fluid against teeth and a servo controller controlling
pressure of ejected fluid in response to a sensed surface
condition. The fluid jet can have a diameter of less than 500
microns, a peak relative pressure of at least 1 kilopascal and
velocity of at least 1 meter per second.
Inventors: |
Hunter; Ian W.; (Lincoln,
MA) |
Assignee: |
Massachusetts Institute of
Technology
Cambridge
MA
|
Family ID: |
43760066 |
Appl. No.: |
12/969111 |
Filed: |
December 15, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61286632 |
Dec 15, 2009 |
|
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|
61286651 |
Dec 15, 2009 |
|
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Current U.S.
Class: |
433/27 ; 433/216;
433/80; 433/89 |
Current CPC
Class: |
A61C 19/063 20130101;
A61C 17/02 20130101 |
Class at
Publication: |
433/27 ; 433/216;
433/80; 433/89 |
International
Class: |
A61C 17/02 20060101
A61C017/02; A61C 17/00 20060101 A61C017/00 |
Claims
1. A method of tooth treatment comprising: sensing a surface
condition of tooth or gum; and controlling ejection of a fluid jet
against the tooth based on the sensed condition.
2. The method of claim 1 wherein the fluid is liquid.
3. The method of claim 2 wherein the fluid is carried in a
self-contained reservoir in a handle of a fluid ejection
device.
4. The method of claim 3 wherein the reservoir is less than 100
milliliters.
5. The method of claim 2 wherein the liquid is a cleansing
solution.
6. The method of claim 2 wherein the liquid contains cleaning
particles.
7. The method of claim 1 wherein the jet is of a diameter of less
than 500 microns.
8. The method of claim 1 wherein the jet is of a diameter of less
than 200 microns.
9. The method of claim 1 wherein the ejection is controlled at a
bandwidth of at least 10 hertz.
10. The method of claim 1 wherein the ejection is controlled at a
bandwidth of at least 50 hertz.
11. The method of claim 1 wherein the ejection is controlled at a
bandwidth of at least 100 hertz.
12. The method of claim 1 wherein the ejection is controlled at a
bandwidth of at least 1 kilohertz.
13. The method of claim 1 wherein the fluid is ejected at a peak
relative pressure of at least 1 kilopascal.
14. The method of claim 1 wherein the fluid is ejected at a peak
relative pressure of at least 100 kilopascals.
15. The method of claim 1 wherein the fluid is ejected at velocity
of at least 1 meter per second.
16. The method of claim 1 wherein the fluid is ejected at velocity
of at least 10 meters per second.
17. The method of claim 1 wherein the ejection is controlled to
clean teeth at high pressure and to reduce pressure applied to
gum.
18. The method of claim 17 wherein the ejection is controlled to
clean plaque.
19. The method of claim 17 wherein less than 100 milliliters of
liquid is ejected per teeth cleaning session.
20. The method of claim 1 to remove soft tooth.
21. The method of claim 1 further comprising automatically scanning
the fluid jet relative to a handle of an injection device.
22. The method of claim 1 wherein the fluid is ejected by means of
a fluid ejector comprising a stationary magnet assembly providing a
magnetic field and a coil assembly, slidably disposed with respect
to the magnet assembly, the coil assembly driving ejection of the
fluid jet.
23. The method of claim 1 wherein sensing the surface condition
comprises measuring a response of tissue to a mechanical
perturbation.
24. The method of claim 23 wherein the mechanical perturbation
comprises applied force and the measured response comprises
deformation of the tissue.
25. The method of claim 23 further comprising mechanically
disturbing the tissue with the fluid jet.
26. The method of claim 22 wherein measuring a response comprises
measuring pressure of the fluid.
27. The method of claim 26 wherein measuring pressure comprises
sensing strain of a fluid reservoir.
28. The method of claim 26 wherein measuring pressure comprises
sensing position of an actuator driving the ejection of the
fluid.
29. The method of claim 1 wherein sensing the surface condition
comprises sensing an acoustic signal reflected from tissue.
30. The method of claim 29 wherein the acoustic signal travels
through the fluid jet.
31. The method of claim 29 wherein the acoustic signal is sensed
using a piezo-electric transducer.
32. The method of claim 29 further comprising generating the
acoustic signal.
33. The method of claim 32 wherein the acoustic signal is generated
and sensed using a piezo-electric transducer.
34. The method of claim 29 wherein the acoustic signal comprises a
stochastic signal.
35. The method of claim 29 wherein sensing the surface condition
further comprises measuring tissue deformation with applied force
using the sensed acoustic signal.
36. The method of claim 35 wherein the force is applied using the
fluid jet.
37. The method of claim 1 further comprising sensing motion of a
fluid ejector and controlling the ejection of the fluid jet based
on the sensed motion.
38. The method of tooth treatment comprising: ejecting a fluid jet
against the tooth, the jet having a diameter of less than 500
microns, a peak relative pressure of at least 1 kilopascal and
velocity of at least 1 meter per second.
39. The method of claim 38 wherein the fluid is liquid.
40. The method of claim 39 wherein the fluid is carried in a
self-contained reservoir in a handle of a fluid ejection
device.
41. The method of claim 40 wherein the reservoir is less than 100
milliliters.
42. The method of claim 38 wherein the jet is of a diameter of less
than 200 microns.
43. The method of claim 38 wherein the fluid is ejected at a peak
relative pressure of at least 100 kilopascals.
44. The method of claim 38 wherein the fluid is ejected at velocity
of at least 10 meters per second.
45. The method of claim 38 wherein the fluid jet is controlled at a
bandwidth of at least 10 hertz.
46. The method of claim 38 wherein the fluid jet is controlled at a
bandwidth of at least 50 hertz.
47. The method of claim 38 wherein the fluid jet is controlled at a
bandwidth of at least 100 hertz.
48. The method of claim 38 wherein the fluid jet is controlled at a
bandwidth of at least 1 kilohertz.
49. The method of claim 38 for removing plaque from teeth.
50. The method of claim 38 further comprising automatically
scanning the fluid jet relative to a handle of an injection
device.
51. The method of claim 38 wherein the fluid is ejected by means of
a fluid ejector comprising a stationary magnet assembly providing a
magnetic field and a coil assembly, slidably disposed with respect
to the magnet assembly, the coil assembly driving ejection of the
fluid jet.
52. A hand-held tooth treatment device comprising: a housing
configured to be held on hand; a fluid ejector positioned at an end
of the housing that ejects fluid against teeth in a scanning
movement relative to the housing.
53. The device of claim 52 wherein the fluid is liquid.
54. The device of claim 53 further comprising a self-contained
reservoir of the liquid in the housing.
55. The device of claim 54 wherein the reservoir is less than 100
milliliters.
56. The device of claim 52 wherein the scan is greater than 1
millimeter.
57. The device of claim 52 further comprising a servo controller
controlling pressure of ejected fluid in response to a sensed
surface condition.
58. The device of claim 57 wherein the sensed surface condition
comprises a mechanical property of tissue.
59. The device of claim 57 further comprising a pressure sensor
that senses pressure of the fluid in the ejector.
60. The device of claim 59 wherein the pressure sensor comprises a
strain gauge that senses strain of a reservoir of the ejector.
61. The device of claim 59 wherein the pressure sensor comprises a
position sensor that senses position of an actuator driving the
ejection of the fluid.
62. The device of claim 52 further comprising a distance sensor
that senses distance of the ejector from a tissue surface.
63. The device of claim 62 wherein the distance sensor comprises a
piezo-electric transducer and the distance is sensed using an
acoustic signal.
64. The device of claim 52 further comprising a servo controller
controlling pressure of ejected fluid in response to a sensed
motion of the ejector.
65. A method of tooth treatment comprising: ejecting a fluid jet
against the tooth; and scanning the fluid jet relative to a handle
of an injection device.
66. The method of claim 65 wherein the fluid is liquid.
67. The method of claim 65 further comprising controlling pressure
of ejected fluid based on a sensed surface condition.
68. The method of claim 65 further comprising controlling pressure
of ejected fluid based on a sensed motion of the injection
device.
69. The method of claim 65 for removing plaque from tooth.
70. A tooth treatment device comprising: a fluid ejector that
ejects fluid against teeth; a servo controller controlling pressure
of ejected fluid in response to a sensed surface condition.
71. The device of claim 70 wherein the fluid is liquid.
72. The device of claim 71 further comprising a housing configured
to be held on hand, the fluid ejector being positioned at an end of
the housing.
73. The device of claim 72 further comprising a self-contained
reservoir of the liquid in the housing.
74. The device of claim 73 wherein the reservoir is less than 100
milliliters.
75. The device of claim 70 wherein the sensed surface condition
comprises a mechanical property of tissue.
76. The device of claim 70 further comprising a pressure sensor
that senses pressure of the fluid in the ejector, and wherein the
surface condition is sensed based on the sensed pressure.
77. The device of claim 70 further comprising an acoustic
transducer that senses an acoustic signal reflected off tissue, and
wherein the surface condition is sensed based on the reflected
acoustic signal.
78. A tooth treatment device comprising a fluid ejector that ejects
a fluid jet against the tooth, the jet having a diameter of less
than 500 microns, a peak relative pressure of at least 1 kilopascal
and velocity of at least 1 meter per second.
79. The device of claim 78 further comprising a servo controller
controlling pressure of ejected fluid in response to a sensed
surface condition.
80. The device of claim 79 wherein the sensed surface condition
comprises a mechanical property of tissue.
81. The device of claim 79 further comprising an acoustic
transducer that senses an acoustic signal reflected off tissue, and
wherein the surface condition is sensed based on the reflected
acoustic signal.
82. The device of claim 78 further comprising a housing configured
to be held on hand, the fluid ejector being positioned at an end of
the housing.
83. The device of claim 82 wherein the fluid is ejected in a
scanning movement relative to the housing.
Description
RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/286,632, filed on Dec. 15, 2009, and U.S.
Provisional Application No. 61/286,651, filed on Dec. 15, 2009. The
entire teachings of the above applications are incorporated herein
by reference.
BACKGROUND OF THE INVENTION
[0002] In the oral cavity, indigenous bacteria are often associated
with two major oral diseases; caries and periodontitis [H. Marcotte
and M. C. Lavoie, Oral microbial ecology and the role of salivary
immunoglobulin A, Micro Mol Bio 62 (1998) 71-109]. The diverse
structures within the mouth (i.e. the tooth surface, subgingival
space, and tongue) support several different microbial communities.
The supragingival environment of the oral cavity is regulated by
saliva, a complex mixture of water, electrolytes (e.g. sodium,
potassium, calcium, chloride, magnesium, bicarbonate, phosphate),
enzymes (e.g. lysozyme, lactoferrin, peroxidase), proteins (e.g.
sIgA, glycoproteins etc.), vitamins, hormones, urea and nitrogenous
products. The less accessible subgingival environment is bathed by
the gingival crevicular fluid (GCF), a plasma exudate containing
proteins, albumin, leukocytes, immunoglobulins, and complement.
[0003] Good oral hygiene requires that one sustain a healthy oral
ecosystem. However, the boundaries between the soft mucosa and hard
teeth are ripe for bacterial colonization (e.g. the gingival
crevice or sulcus). The sulcus together with the area between the
teeth (i.e. approximate surface), and the pits and fissures of the
biting surface are not easily cleaned by brushing (i.e. mechanical
friction). Microorganisms tend to colonize these areas to form
dental plaque; a biofilm of microorganisms and salivary components.
If not removed, plaque can lead to caries or periodontal disease
(e.g. gingivitis and possibly periodontitis). Plaque and calculus
can be removed with or without electrically driven hand instruments
in the dental office. Calculus, a form of hardened plaque, forms
along the gum line and within the sulcus leading to inflammation
that can eventually lead to deep pockets between the teeth and gum
and loss of bone that holds the tooth in place. Human periodontitis
is associated with a widely diverse and complex subgingival
microbiota [Daniluk, T., Tokajuk, G., Cylwik-Rokicka, D.,
Rozkiewics, D., Zaremba, M. L., and Stokowska, W., Aerobic and
anaerobic bacteria in subgingival and supragingival plaques of
adult patients with periodontal disease, Adv Med Sci 51: (2006)
81-85].
[0004] While there are commercially available water jet devices for
dental cleaning, they are limited for the most part to the removal
of debris. The pumps used in these units are often noisy, which can
contribute to patient discomfort. Seating or mating the tip with
the water jet is sometimes problematic leading to leakage and
ineffective or less than optimal irrigation. While some devices
have adjustable controls, many do not provide good control.
[0005] Sensing devices for diagnosing oral health and/or hygiene
are currently either in the research and development stage or are
formatted for use by trained professionals. Many devices are not
user friendly and not suitable for day to day use by consumers.
SUMMARY OF THE INVENTION
[0006] A method of tooth treatment includes sensing a surface
condition of tooth or gum and controlling ejection of a fluid jet
against the tooth based on the sensed condition.
[0007] The fluid may be a liquid and may be carried in a
self-contained reservoir in a handle of a fluid ejection device.
The reservoir can be less than 100 milliliters. The liquid can be a
cleansing solution and may contain cleaning particles.
[0008] In one embodiment, the fluid jet is of a diameter of less
than 500 microns. The jet may be of a diameter of less than 200
microns. The ejection may be controlled at a bandwidth of at least
10 Hertz, of at least 50 Hertz, of at least 100 Hertz, or of at
least 1 kilo Hertz. The fluid may be ejected at a peak relative
pressure of at least 1 kilopascal or of at least 100 kilopascals,
and at a velocity of at least 1 meter per second or of at least 10
meters per second. The ejection can be controlled to clean teeth at
high pressure and to reduce pressure applied to gum and may be
controlled to clean plaque. Less than 100 milliliters of liquid may
be ejected per teeth cleaning session. In some embodiments, the
method may be used to remove soft tooth. The method may further
include automatically scanning the fluid jet relative to a handle
of an injection device.
[0009] In an embodiment, the fluid is ejected by means of a fluid
ejector comprising a stationary magnet assembly providing a
magnetic field and a coil assembly, slidably disposed with respect
to the magnet assembly, the coil assembly driving ejection of the
fluid jet.
[0010] In some embodiments, sensing the surface condition includes
measuring a response of tissue to a mechanical perturbation. The
mechanical perturbation can include applied force and the measured
response can include deformation of the tissue. The method may
further include mechanically disturbing the tissue with the fluid
jet. Measuring a response of the tissue may include measuring
pressure of the fluid. Measuring pressure can include sensing
strain of a fluid reservoir and may include sensing position of an
actuator driving the ejection of the fluid. In an embodiment,
sensing the surface condition includes sensing an acoustic signal
reflected from tissue. The acoustic signal may travels through the
fluid jet and may be sensed using a piezo-electric transducer. The
method may further include generating the acoustic signal. The
acoustic signal may be generated and sensed using a piezo-electric
transducer, and may include a stochastic signal. Further, sensing
the surface condition may include measuring tissue deformation with
applied force using the sensed acoustic signal. The force can be
applied using the fluid jet. In some embodiments, the method may
further include sensing motion of a fluid ejector and controlling
the ejection of the fluid jet based on the sensed motion.
[0011] A method of tooth treatment includes ejecting a fluid jet
against the tooth, the jet having a diameter of less than 500
microns, a peak relative pressure of at least 1 kilopascal and
velocity of at least 1 meter per second. The method may be used for
removing plaque from teeth and may include automatically scanning
the fluid jet relative to a handle of an injection device.
[0012] A hand-held tooth treatment device includes a housing
configured to be held on hand and a fluid ejector positioned at an
end of the housing that ejects fluid against teeth in a scanning
movement relative to the housing. The scan may be greater than 1
millimeter. The device may further include a servo controller
controlling pressure of ejected fluid in response to a sensed
surface condition, such as a mechanical property of tissue.
Further, the device can include a pressure sensor that senses
pressure of the fluid in the ejector. The pressure sensor may
include a strain gauge that senses strain of a reservoir of the
ejector. Alternatively or in addition, the pressure sensor can
include a position sensor that senses position of an actuator
driving the ejection of the fluid. The device may further include a
distance sensor that senses distance of the ejector from a tissue
surface. In some embodiments, the distance sensor includes a
piezo-electric transducer and the distance is sensed using an
acoustic signal. Further, the device may include a servo controller
controlling pressure of ejected fluid in response to a sensed
motion of the ejector.
[0013] A method of tooth treatment includes ejecting a fluid jet
against the tooth and scanning the fluid jet relative to a handle
of an injection device. Further, the method of tooth treatment can
include controlling pressure of ejected fluid based on a sensed
surface condition and, alternatively or in addition, based on a
sensed motion of the injection device. The method may be used for
removing plaque from tooth.
[0014] A tooth treatment device includes a fluid ejector that
ejects fluid against teeth and a servo controller controlling
pressure of ejected fluid in response to a sensed surface
condition. The device may further include a housing configured to
be held on hand, the fluid ejector being positioned at an end of
the housing. Further, the device can include a self-contained
reservoir of the liquid in the housing and the reservoir may be
less than 100 milliliters. In some embodiments, the device may
further include a pressure sensor that senses pressure of the fluid
in the ejector, and wherein the surface condition is sensed based
on the sensed pressure. Alternatively or in addition, the device
may further include an acoustic transducer that senses an acoustic
signal reflected off tissue, and wherein the surface condition is
sensed based on the reflected acoustic signal.
[0015] A tooth treatment device includes a fluid ejector that
ejects a fluid jet against the tooth, the jet having a diameter of
less than 500 microns, a peak relative pressure of at least 1
kilopascal and velocity of at least 1 meter per second.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The foregoing will be apparent from the following more
particular description of example embodiments of the invention, as
illustrated in the accompanying drawings in which like reference
characters refer to the same parts throughout the different views.
The drawings are not necessarily to scale, emphasis instead being
placed upon illustrating embodiments of the present invention.
[0017] FIG. 1 is a schematic block diagram of one embodiment of a
controllable, needle-free transfer device for cleaning teeth, gums,
and other areas of the mouth;
[0018] FIG. 2A is a partial cut-away perspective diagram of an
embodiment of a controllable needle-free transfer device;
[0019] FIG. 2B are graphs depicting force-versus-time profiles of
exemplary force components used for fluid delivery and for tissue
identification, the force components being generated by the
controllable electromagnetic actuator of FIG. 2A;
[0020] FIG. 3 is a partial cut-away perspective diagram of the
device of FIG. 2A illustrating scanning of the device;
[0021] FIGS. 4A and 4B are graphs depicting pressure versus time,
the measure being fluid pressure sensed using a strain gauge and a
position sensor, respectively;
[0022] FIG. 4C is a graph of peak pressures sensed during ejection
of fluid against materials of different surface properties;
[0023] FIG. 4D is a graph of pressure versus angle of injection
against a surface;
[0024] FIGS. 5A-5D are perspective diagrams showing delivery of
water and black beads to the gum line and sulcus;
[0025] FIG. 6 is a top perspective diagram of an exemplary detector
for detecting an analyte from a sample collected in a disposable
tube;
[0026] FIGS. 7A and 7B are schematic block diagrams of a
needle-free transport device providing sampling and analysis
capability, respectively shown in the sampling and fluid ejection
configurations;
[0027] FIG. 8 is a top perspective diagram of an exemplary detector
for detecting an analyte using a polymer strip;
[0028] FIG. 9A is a schematic diagram showing binding of an analyte
(antibody) to a solid support (polypyrrole film strip);
[0029] FIG. 9B is a graph of light absorbance versus antigen
concentration;
[0030] FIG. 10 is a schematic diagram showing a detector for
detecting a marker or analyte of oral health status.
DETAILED DESCRIPTION OF THE INVENTION
[0031] A description of example embodiments of the invention
follows.
[0032] The entire teachings of U.S. patent application Ser. No.
10/277,722, filed on Oct. 21, 202, entitled "Impedance Sensor"
(Attorney Docket No.: 0050.2035-000, Client Reference No.:
MIT-9486), now U.S. Pat. No. 7,645,263, issued on Jan. 12, 2010;
U.S. Pat. No. 6,939,323, issued on Sep. 6, 2005, entitled
"Needleless Injector" (Attorney Docket No.: 0050.2036-001; Client
Ref. No.: MIT-9496); U.S. Pat. No. 7,425,204, issued on Sep. 16,
2008, entitled "Needleless Injector" (Attorney Docket No.:
0050.2036-016; Client Ref. No.: MIT-9496); U.S. patent application
Ser. No. 12/459,866, filed on Jul. 8, 2009, entitled
"Bi-Directional Motion of a Lorentz-Force Actuated Needle-Free
Injector (NFI)" (Attorney Docket No.: 0050.2124-001; Client Ref.
No.: MIT-13318); U.S. Pending patent application Ser. No.
12/872,630, filed on Aug. 31, 2010, entitled "Nonlinear System
Identification Techniques and Device For Discovering Dynamic And
Static Tissue Properties" (Attorney Docket No.: 0050.2133-002;
Client Ref. No.: MIT-13836); U.S. Pat. No. 7,530,975, issued on May
12, 2009, entitled "Measuring Properties of an Anatomical Body"
(Attorney Docket No.: 0050.2048-006; Client Ref. No.: MIT-9894);
and U.S. Published Application No. US 2007/0191758, published on
Aug. 16, 2007, entitled "Controlled Needle-Free Transport"
(Attorney Docket No. 0050.2079-005; Client Ref. No.: MIT-11511) are
incorporated herein by reference. These Applications and Patents
relate to sensors and injectors that may be utilized in
implementing the present invention.
[0033] Embodiments of the present invention relate to a needle-free
device for cleaning the teeth, the gums, and other areas of the
mouth. The embodiments of the present invention may be used for
cleaning and diagnosis of dental and medical conditions in human or
animals. Certain embodiments include a fine jet injector that
transfers high pressured liquid (e.g., water, liquid designed for
cleaning of the mouth, liquid designed for diagnosis of medical or
dental conditions, and etc.) to remove and blast off plaque from
the human teeth. The jet injector is servo-controlled to transfer
the liquid and control the pressure of the fluid in the vicinity of
soft tissue (e.g., gums). As such, the high pressure liquid will
remove plaque from the teeth without penetrating the gums. The
device may operate in real time by determining mechanical
properties of the transfer site and distinguish between hard tissue
and soft tissue based on the mechanical properties.
[0034] The needle-free device includes an actuator capable of
generating a high-speed, high-pressure pulse that is both
controllable and highly predictable. The device may be combined
with a servo-controller receiving inputs from one or more sensors.
Further, the device may adjust or tailor the pressure profile of a
transfer in real-time, during the course of the transfer,
responsive to sensed physical properties of tissue and teeth. For
example, the device may be able to distinguish soft tissue (e.g.,
gums, gum lines, and tongue) from the teeth.
[0035] The jet injector may include sensors that detect respective
physical properties of the transfer site. The physical properties
can be used to servo control the jet injector and tailor the
injection pressure, and, therefore, the depth of penetration of
fluid into for a particular region. For instance, when the device
is used on the gums, the sensor detects the softness of the gums,
and the controller uses the properties of the gums and consequently
reduces the transfer pressure. The transfer pressure can be
adjusted, for example, by controlling the electrical input signal
applied to the injector and/or the current pulse rise time and/or
duration. When used on hard enamel (teeth), the controller may
increase the transfer pressure. The transfer pressure may be
adjusted depending on location of the liquid transfer, for example,
the gums versus the tongue. The transfer pressure can also be
tailored to deliver a substance just underneath the gum line or
deep into gums. Moreover, the transfer pressure may be varied over
time.
[0036] Since oral plaque is usually stored as deep as one
millimeter under the gum line, the controller of the needle-free
device can distinguish between the teeth, gums, and the gum line by
considering the physical properties of the teeth and the soft
tissue and adjust the transfer pressure on each of these body parts
accordingly.
[0037] In certain embodiments, the needle-free injector generates a
jet pressure and transfers high pressure liquid that can remove the
plaque from the teeth. The peak liquid pressure may be as low as 1
Kilo Pascal. In some embodiments up to 100 Kilo Pascal of relative
water pressure may be applied.
[0038] Jets of less than 500 microns are generally employed. In
certain embodiments, very fine jets may be employed. For example,
jets having diameter of less than five micro meters may be
employed. In one embodiment, the jet injectors may have a diameter
of less than 200 micrometers.
[0039] The needle-free device is servo-controlled to transfer the
fluid and control the pressure of the fluid in the vicinity of soft
tissue (e.g., gums) and the teeth. Due to the high level of control
offered by the device, the amount of fluid transferred into the
mouth may be significantly reduced. In some embodiments, a tooth
cleaning liquid having appropriate cleaning agents may be jet
injected into the mouth, teeth, or the gums to help with blasting
of plaque and maintaining oral health. Additional substances may be
included in the liquid injected into the mouth. For example,
substances having bacteria and fungus fighting agents, whitening
agents, or breath freshening agents may be employed.
[0040] In some embodiments, the needle-free device may further
include one or more electrical impedance sensors that can be used
to distinguish between soft tissue (gums and tongue) and the teeth.
The impedance testing also provides a convenient way of determining
the depth of penetration. The impedance sensor may include an
electrode positioned to measure the impedance of a portion of the
target area between the electrode and ground to indicate the depth
of penetration into the target area.
[0041] In certain embodiments, two or more jet injectors may be
employed with one of the jet injectors serving as a ground
connection for impedance measurements. In some embodiments, a
conductive fluid can be used for cleaning or diagnosis. In these
embodiments, the body, through the lip, when it comes in contact
with the injector, provides the ground connection for the impedance
measurements.
[0042] In some embodiments, the needle-free device includes a
reservoir for storing the fluid and a controllable electromagnetic
actuator in communication with the reservoir. The controllable
electromagnetic actuator may include a stationary magnet assembly
providing a magnetic field; and a coil assembly. The coil assembly
receives an electrical input and generates in response a force
corresponding to the received input. The force results from
interaction of an electrical current within the coil assembly and
the magnetic field and causes the transfer of the fluid between the
reservoir and the mouth. The needle-free device can include a
sensor that senses physical properties of the transfer site and
causes the servo-controller to generate the electrical input
responsive to the sensed physical property. In order to measure the
physical properties, ranging techniques using acoustic waves or
laser beams may be applied to find deformation of teeth or gum
lines. Acoustic waves may be used in combination with a fluid jet,
where the pressure of the fluid jet applies a force to the target
tissue to perturb the target tissue and the acoustic waves are used
to sense the deformation or displacement of the tissue in response
to the perturbation. The acoustic signal can propagate through the
fluid jet and may include a sinusoidal and/or stochastic
signal.
[0043] Example embodiments may include a Lorentz-Force actuator to
provide reversibility for the device. In such embodiments, a fluid
can be pumped into the mouth to blast off and remove plaque and the
removed material may then be removed from the mouth using the
reversible actuator. The Lorentz force actuator exerts a force. The
force can be used for needle-free transfer of the substance between
the reservoir and the mouth. The injector can determine changes in
response to the forces and determine individual target area
properties based on the response to the forces. In certain
embodiments, stochastic (random) or pseudo-random information can
be employed to create a model (e.g., non-parametric model) of
tissue properties.
[0044] Example embodiments may include a piezoelectric actuator to
provide high frequency pulses of the fluid jet. The device may have
a minimum bandwidth of approximately 10 Hz (Hertz). In certain
embodiments the device may have a bandwidth of 50 Hz, 100 Hz, or
100 KHz.
[0045] Certain embodiments may include sensors and related
technologies for analyzing materials removed from the mouth such as
plaque, saliva, and etc. The analyzed results may be used to
distinguish between healthy and unhealthy tissue in the mouth. In
some embodiments, the liquid transferred into the mouth may include
biomarkers for verifying oral health and detecting possible health
issues. In some embodiments, the same liquid containing biomarkers
may be used in cleaning and plaque removal.
[0046] In some embodiments, the needle-free device may be used in
diagnosis of oral conditions. For example, the device may be used
to determine if a tooth has a cavity or is decaying. Since the
mechanical properties of a decaying tooth are different from that
of a healthy tooth, the device can diagnose a decaying tooth by
determining a change in the mechanical property of the tooth.
Microelectromechanical Systems (MEMS) along with accelerometers may
be used to determine the location of a decaying tooth.
[0047] The device may be coupled to a Computer-Aided Diagnosis
model of the mouth to determine health status of every surface. The
device may transfer a fluid that is to be used on a daily basis for
cleaning and a second fluid for diagnosis that is to be used on a
less frequent basis. Certain embodiments may employ Raman
spectroscopy techniques to distinguish healthy and unhealthy
tissue. The data obtained regarding the health of the mouth may be
fed into a database, or transferred, possibly via a wireless
module, for further evaluation or analysis.
[0048] The device may transfer as much as 10 microliters of fluid,
e.g., liquid, per second. The liquid may be transferred at a peak
pressure of 1 kilo Pascal to loosen food. In certain embodiments,
an average pressure of up to 100 Mega Pascal may be used to loosen
plaque. The device may operate at a velocity as low as 1 meter per
second (m/s). In some embodiments, velocities as high as 10 m/s or
higher (e.g., 2/3 of the speed of sound) may be used.
[0049] Pulses can be used to dynamically control (e.g.,
servo-control) the magnitude, direction and duration of the force
during the course of an actuation cycle. In certain embodiments,
the device includes an actuator capable of generating a high-speed,
high-pressure pulse that is both controllable and highly
predictable. The device also includes the ability to pulse shape to
use different waveforms for each cycle. In certain embodiments,
fine sinusoidal pulses may be employed to approximate a square
wave. For example, a sinusoidal pulse having a bandwidth of 10
microseconds can be used.
[0050] The device may be coupled to multiple reservoirs. In one
example embodiment, the device includes two reservoirs arranged
such that one reservoir includes a larger amount of fluid compared
to the other reservoir. At each cycle, a square wave is used to
control the direction and duration of the force. At each cycle a
certain amount of fluid is transferred from the second reservoir
into the mouth. At the end of the cycle, a limited amount of liquid
is transferred from the first reservoir into the second
reservoir.
[0051] The device may also be used in drilling the teeth.
Previously, dentists removed cavity by simply feeling soft,
unhealthy enamel from the teeth (while removing healthy enamel in
the process). The device can determine the mechanical properties of
healthy tooth vs. unhealthy tooth and use a combination of velocity
and pressure coupled with an abrasive to drill the unhealthy
portion of the tooth and leave the healthy enamel behind. Drill
heads as small as 50 micrometers in diameter may be used.
[0052] FIG. 1 is a schematic block diagram of a needle-free
transport device or jet injector 100 that may be used in example
embodiments. Device 100 can transfer a substance to or from a
surface of a biological body and may be used to eject a fluid
against tooth 150, gum 155, or other tissue in the oral cavity. The
jet injector 100 can be used to deposit a fluid, including a
medicant or biomarker, into the space between tooth 150 and gum
155. Alternatively of in addition, the same device can be used to
collect a sample from a location at or near the tooth 150 or gum
155 by withdrawing the collected sample into a reservoir 113
[0053] The device 100 typically includes a nozzle 114 to convey the
substance. Namely, substance ejected from the nozzle 114 forms a
jet, the force of the jet determining the depth of penetration. The
nozzle 114 generally contains a flat surface, such as the head 115
and an orifice 101. It is the inner diameter of the orifice 101
that controls the diameter of the transferred stream. Additionally,
the length of an aperture or tube 103, defining the orifice 101
also controls the transfer (e.g., injection) pressure.
[0054] The nozzle 114 can be coupled to a reservoir 113 for
temporarily storing the transferred substance. Reservoir 113 may be
a reservoir of a syringe or ampoule 112. Beneficially, a pressure
is selectively applied to the reservoir 113 using a controllable
actuator. A specially-designed electromagnetic actuator 125 is
configured to generate a high-pressure pulse having a rapid rise
time (e.g., less than 1 millisecond). The actuator 125 can be used
in needle-free injection devices that rely on high-pressure
actuators to inject a formulation beneath the skin. The actuator is
dynamically controllable, allowing for adjustments to the
pressure-versus-time during actuation. At least one advantage of
the electromagnetic actuator over other needle-free devices is its
relatively quiet operation. Actuation involves movement of a freely
suspended coil within a gap, rather than the sudden release of a
spring or the discharge of a gas. Actuation of the freely-moving
coil in the manner described herein results in quiet operation,
which is an important feature as it contributes to reducing pain
and anxiety during administration to the recipient and to others
that may be nearby.
[0055] In more detail, the electromagnetic actuator 125 is
configured to provide a linear force applied to the plunger 126 to
achieve transfer of the substance. Transfer of the force can be
accomplished with a force-transfer member 110, such as a rigid rod
slidably coupled through a bearing 111. The rod may be secured at
either end such that movement of the actuator in either direction
also moves the plunger 126. The bearing restricts radial movement
of the rod 110, while allowing axial movement.
[0056] In some embodiments, the actuator 125 is a Lorentz force
actuator that includes a stationary component, such as a magnet
assembly 105, and a moveable component, such as a coil assembly
104. A force produced within the coil assembly 104 can be applied
to the plunger 126 either directly or indirectly through the rod
110 to achieve transfer of the substance.
[0057] In some embodiments, device 100 may not include a separate
bearing 111. Rather, an interior surface of the housing 102
provides a bearing for the coil assembly 104 allowing axial
movement while inhibiting radial movement.
[0058] In some embodiments, the device 100 includes a user
interface 120 that provides a status of the device. The user
interface may provide a simple indication that the device is ready
for actuation. More elaborate user interfaces 120 can be included
to provide more detailed information, including a liquid crystal
display (LCD), cathode ray tube (CRD), charge-coupled device (CCD),
or any other suitable technology capable of conveying detailed
information between a user and the device 100. Thus, user interface
120 may also contain provisions, such as a touch screen to enable
an operator to provide inputs as user selections for one or more
parameters. Thus, a user may identify parameters related to dose,
sample, parameters related to the biological body, such as age,
weight, etc.
[0059] A power source 106 provides an electrical input to the coil
assembly 104 of the actuator 125. An electrical current applied to
the coil assembly 104 in the presence of a magnetic field provided
by the magnet assembly 105 will result in a generation of a
mechanical force capable of moving the coil assembly 104 and
exerting work on the plunger 126 of the syringe 112. The
electromagnetic actuator is an efficient force transducer
supporting its portability.
[0060] A controller 108 is electrically coupled between the power
source 106 and the actuator 125, such that the controller 108 can
selectively apply, withdraw and otherwise adjust the electrical
input signal provided by the power source 106 to the actuator 125.
The controller 108 can be a simple switch that is operable by a
local interface. For example, a button provided on the housing 102
may be manipulated by a user, selectively applying and removing an
electrical input from the power source 106 to the actuator 125. In
some embodiments, the controller 108 includes control elements,
such as electrical circuits, that are adapted to selectively apply
electrical power from the power source 106 to the actuator 125, the
electrical input being shaped by the selected application. Thus,
for embodiments in which the power source 106 is a simple battery
providing a substantially constant or direct current (D.C.) value,
the electrical input can be shaped by the controller to provide a
different or even time varying electrical value. In some
embodiments, the controller 108 includes an on-board
microprocessor, or alternatively an interconnected processor or
personal computer providing multifunction capabilities. A power
amplifier (not shown) may be included in the controller 108 or,
alternatively or in addition, in power source 106.
[0061] In some embodiments, the needle-free device 100 includes a
remote interface 118. The remote interface 118 can be used to
transmit information, such as the status of the device 100 or of a
substance contained therein to a remote source, such as a hospital
computer or a drug manufacturer's database. Alternatively or in
addition, the remote interface 118 is in electrical communication
with the controller 108 and can be used to forward inputs received
from a remote source to the controller 108 to affect control of the
actuator 125.
[0062] The remote interface 118 can include a network interface,
such as a local area network interface (e.g., Ethernet). Thus,
using a network interface card, the device 100 can be remotely
accessed by another device or user, using a personal computer also
connected to the local area network. Alternatively or in addition,
the remote interface 118 may include a wide-area network interface.
Thus, the device 100 can be remotely accessed by another device or
user over a wide-area network, such as the World-Wide Web. In some
embodiments, the remote interface 118 includes a modem capable of
interfacing with a remote device/user over a public-switched
telephone network. In yet other embodiments, the remote interface
118 includes a wireless interface to access a remote device/user
wirelessly. The wireless interface 118 may use a standard wireless
interface, such as Wi-Fi standards for wireless local area networks
(WLAN) based on the IEEE 802.11 specifications; new standards
beyond the 802.11 specifications, such as 802.16(WiMAX); and other
wireless interfaces that include a set of high-level communication
protocols such as ZigBee, designed to use small, low power digital
radios based on the IEEE 802.15.4 standard for wireless personal
area networks (WPANs).
[0063] In some embodiments the controller receives inputs from one
or more sensors adapted to sense a respective physical property.
For example, the device 100 includes a transducer, such as a
position sensor 116B used to indicate location of an object's
coordinates (e.g., the coil's position) with respect to a selected
reference. Similarly, a displacement may be used to indicate
movement from one position to another for a specific distance.
Beneficially, the sensed parameter can be used as an indication of
the plunger's position and therefore an indication of dose. In some
embodiments, a proximity sensor may also be used to indicate when a
part of the device, such as the coil, has reached a critical
distance. This may be accomplished by sensing the position of the
plunger 126, the force-transfer member 110, or the coil assembly
104 of the electromagnetic actuator 125. For example, an optical
sensor such as an optical encoder can be used to count turns of the
coil to determine the coil's position. Other types of sensors
suitable for measuring position or displacement include inductive
transducers, resistive sliding-contact transducers, photodiodes,
and linear-variable-displacement-transformers (LVDT).
[0064] Other sensors, such as a force transducer 116A can be used
to sense the force applied to the plunger 126 by the actuator 125.
As shown, a force transducer 116A can be positioned between the
distal end of the coil assembly and the force transfer member 110,
the transducer 116A sensing force applied by the actuator 125 onto
the force-transfer member 110. As this member 110 is rigid, the
force is directly transferred to the plunger 126. The force tends
to move the plunger 126 resulting in the generation of a
corresponding pressure within the reservoir 113. A positive force
pushing the plunger 126 into the reservoir 113 creates a positive
pressure tending to force a substance within the reservoir 113 out
through the nozzle 114. A negative force pulling the plunger 126
proximally away from the nozzle 114 creates a negative pressure or
vacuum tending to suck a substance from outside the device through
the nozzle 114 into the reservoir 113. The substance may also be
obtained from another reservoir or ampoule, the negative pressure
being used to pre-fill the reservoir 113 with the substance.
Alternatively or in addition, the substance may come from the
biological body representing a sampling of blood, tissue, and or
other interstitial fluids. In some embodiments, a pressure
transducer (not shown) can also be provided to directly sense the
pressure applied to a substance within the chamber or reservoir
113. In addition, the position sensor 116B may sense the position
of the coil which may be used to indirectly measure the pressure
within the reservoir 113.
[0065] An electrical sensor 116C may also be provided to sense an
electrical input provided to the actuator 125. The electrical
sensor may sense one or more of coil voltage and coil current.
Other sensors may include for example a gyrometer 116D, an
accelerometer 116E, a strain gauge 116F, a temperature sensor 116G,
an acoustic sensor or transducer 116H, and/or barometric pressure
sensor 116J. The gyrometer 116D may include a 3-axis gyroscope and
the accelerometer 116E may include a 3-axis accelerometer. The
sensors 116A, 116B, 116C, 116D, 116E, 116F, 116G, 116H, and 116J
(generally 116) are coupled to the controller 108 providing the
controller 108 with the sensed properties. The controller 108 may
use one or more of the sensed properties to control application of
an electrical input from the power source 106 to the actuator 125,
thereby controlling pressure generated within the syringe 112 to
produce a desired transfer performance. For example, a position
sensor can be used to servo-control the actuator 125 to
pre-position the coil assembly 104 at a desired location and to
stabilize the coil 104 once positioned, and conclude an actuation
cycle. Thus, movement of the coil assembly 104 from a first
position to a second position corresponds to transfer of a
corresponding volume of substance. The controller can include a
processor programmed to calculate the volume based on position
given the physical size of the reservoir.
[0066] An actuation cycle, generally corresponds to initiation of
an electrical input to the actuator 125 to induce transfer of a
substance and conclusion of the electrical input to halt transfer
of the substance. A servo-control capability combined with the
dynamically controllable electromagnetic actuator 125 enables
adjustment of the pressure during the course of an actuation cycle.
One or more of the sensors 116 can be used to further control the
actuation cycle during the course of the transfer, or cycle.
Alternatively or in addition, one or more of local and remote
interfaces can also be used to further affect control of the
actuation cycle.
[0067] In some implementations, the controller 108 is coupled with
one or more sensors 116, or one or more other sensors (not shown),
that detect respective physical properties of the biological body.
This information can be used to servo control the actuator 125 to
tailor the injection pressure. For instance, when the device 100 is
used on the gums, the sensor detects the softness of the gums, and
the controller 108 uses the properties of the gums and consequently
reduces the injection pressure. The injection pressure can be
adjusted, for example, by controlling the electrical input signal
applied to the actuator 125 and/or the current pulse rise time
and/or duration. When used on teeth, the controller may increase
the injection pressure. The injection pressure may be adjusted
depending on location of the skin on the body, for example, the
face versus the arm of the patient. Moreover, the injection
pressure may be varied over time. For instance, in some
implementations, a large injection pressure is initially used to
loosen cavity, and then a lower injection pressure is used to
loosen food.
[0068] For example, the controller 108 may be coupled with an
acoustic sensor 1161, such as a piezo-electric sensor or
transducer, to measure the deformation of the biological body in
response to a mechanical perturbation. The piezo-electric
transducer may be located at the tip of the device, for example, at
or near nozzle 114. The transducer may be in fluid communication
with the fluid ejected through nozzle 114 and may also be in fluid
communication with reservoir 113. In one embodiment, the
piezo-electric transducer can be located at the distal end of
plunger 126 (see FIG. 2A). The piezo-electric transducer may emit
acoustic signals and sense acoustic signal reflected from the
biological body. The acoustic signal may include a high-frequency
and/or stochastic signal.
[0069] In more detail, the power source 106 can be external or
internal to the device 100 or be rechargeable. The power source 106
can include a replaceable battery. Alternatively, the power source
106 includes a rechargeable device, such as a rechargeable battery
(e.g., gel batteries; lead-acid batteries; Nickel-cadmium
batteries; Nickel metal hydride batteries; Lithium ion batteries;
and Lithium polymer batteries). In some embodiments, the power
source 106 includes a storage capacitor. For example, a bank of
capacitors can be charged through another power source, such as an
external electrical power source.
[0070] In more detail, the electromagnetic actuator 125 includes a
conducting coil assembly 104 disposed relative to a magnetic field,
such that an electrical current induced within the coil results in
the generation of a corresponding mechanical force. The
configuration is similar, at least in principle, to that found in a
voice coil assembly of a loud speaker. Namely, the relationship
between the magnetic field, the electrical current and the
resulting force is well defined and generally referred to as the
Lorentz force law.
[0071] Preferably, the coil 104 is positioned relative to a
magnetic field, such that the magnetic field is directed
substantially perpendicular to the direction of one or more turns
of the coil 104. Thus, a current induced within the coil 104 in the
presence of the magnetic field results in the generation of a
proportional force directed perpendicular to both the magnetic
field and the coil (a relationship referred to as the "right hand
rule").
[0072] An exemplary embodiment of a dynamically-controllable
needle-free injection device 200 is shown in FIG. 2A. The device
200 includes a compact electromagnetic actuator 202 having a distal
force plate 204 adapted to abut a proximal end of a plunger 206 of
a syringe or ampoule 208. The ampoule 208 may, for example, be a
commercially available polycarbonate ampoule, such as the INJEX.TM.
ampoule. The device 200 also includes a mounting member 212 to
which a proximal end of the syringe 208 is coupled. A power source
(not shown) may also be disposed proximal to the actuator 202, the
different components being secured with respect to each other
within a housing or shell 216. In some embodiments, a coupler 225
is provided to removably fasten the plunger 206 to the actuator
202. This ensures that the plunger is moved in either direction
responsive to movement of the actuator 202.
[0073] FIG. 2B are graphs depicting force-versus-time profiles of
components of exemplary force applied to . . . reservoir 213 in the
transfer of a substance and in tissue identification, the force
being generated by the controllable electromagnetic actuator of
FIG. 2A. As shown, the actuator may apply a square-wave force
component for fluid delivery that is modulated with a low frequency
sinusoidal signal for tissue perturbation and identification.
Alternative or in addition, the actuator may also apply a
stochastic signal for tissue perturbations.
[0074] As shown in FIG. 2A, device 200 can include a piezo-electric
actuator or transducer 216H located at the distal end of plunger
206. The transducer is in fluid communication with the fluid
ejected through nozzle 214 and in fluid communication with
reservoir 213 of ampoule 208. The piezo-electric transducer may
emit acoustic signals 230 and sense acoustic signals reflected from
the biological body, e.g., the tooth or gum. The acoustic signal
may include a high-frequency and/or stochastic signal. The
piezo-electric transducer may continuously send an acoustic signal
through the fluid and sense the reflection of the signal off a
target surface of the biological body. Information of the emitted
and reflected signal can then be used to continuously determine the
distance of the target surface from the transducer, and may be used
to measure the displacement or deformation of the biological
body.
[0075] Device 200 may include a strain gauge 216F and a position
sensor or linear encoder 216B to sense fluid pressure, including
back pressure from the ejection of the fluid against tissue, such
as tooth, gum, or any other tissue or surface. Sensing pressure
using the strain gauge and/or the position sensor can be used to
measure the reaction of tissue to the sinusoidal signal modulating
the fluid jet and may be used to sense a surface condition of the
tissue.
[0076] FIG. 3 is a partial cut-away perspective diagram of the
device of FIG. 2A illustrating scanning of a fluid jet. The
needle-free device 200 may operate as a hand-held device moving
over the teeth, the gums, the tongue, or other parts of the mouth.
The device may include multiple degrees of freedom to be able to
scan the teeth from various positions and orientations. For
example, the device 200 may scan the teeth in vertical or
horizontal (e.g., left and right) directions. FIG. 3 illustrates
scanning in a horizontal direction as indicated by the arrow 300.
The needle-free device 200 is highly controllable in terms of
pressure, flow, and velocity and can provide for linear, spiral, or
rotary scans, resulting in multi-dimensional coverage of the mouth.
The device 200 can eject a fluid against the teeth and the gum in a
scanning motion, sense a surface condition, and control the
ejection pressure based on the sense condition. For example, device
200 can control fluid ejection to scan with low pressure and, when
on teeth, clean the surface of teeth with high pressure. The
needle-free device 200 may also be used in cleaning the surface of
the tongue since it can detect the softness of the tongue and vary
its transfer pressure.
[0077] In one embodiment, the strain gauge 216F coupled to the
ampoule 208 (FIG. 2A) is high sensitivity, high bandwidth strain
gauge. An example of a suitable strain gauge is a general-purpose
strain gauge made from constantan alloy having a resistance of 120
ohm and gauge factor of about 2. With a 2.5 V activation voltage,
the strain gauge can achieve sensitivity of 5 .mu.V/N and operate
at a background noise level of 0.6 .mu.V. Another example of a
suitable strain gauge with higher sensitivity is a
platinum-tungsten strain gauge having 350 ohm resistance and a
gauge factor of about 4.5. The strain gauge may be coupled to a
controller, such as a NATIONAL INSTRUMENTS.TM. NI CompactRIO
Control and Acquisition System, to power the gauge and collect
measurements at, for example, 25 k Sample/sec.
[0078] FIGS. 4A and 4B are graphs depicting pressure versus time of
fluid pressure sensed using a strain gauge and a position sensor,
respectively. The fluid pressure sensed comprises the pressure due
the actuator ejecting the fluid through a nozzle and the back
pressure from the fluid jet hitting the target material. Target
materials include soft materials, including air (i.e., ejecting a
fluid jet into air), silicone rubber (durometer 30 Shore A), 10%
acrylamide gel, and water, as well as hard materials, including
steel, glass ceramic, PVC-coated polycarbonate, and wood. Some of
the target materials, such as the silicone rubber, are tissue
analogs.
[0079] FIG. 4A shows the pressure sensed using a strain gauge 216F
coupled to the ampoule 208. The strain gauge measures hoop stress
of the ampoule during fluid ejection. FIG. 4B shows the pressure
sensed using a linear encoder 216B that measures the position of
the voice coil of the actuator 202, the position being related to
the force applied by the actuator to the ampoule during fluid
ejection. Both methods of sensing pressure produce pressure
profiles that can be used to distinguish between hard and soft
materials. Both methods may also be used to further distinguish
among the tested materials in the hard and soft group of materials.
The sensed difference in pressure profilesdue to differences in
material hardness is a material property, or surface condition,
that can be used to control the ejection of fluid.
[0080] FIG. 4C is a graph of peak pressure for ejection of fluid
against materials of different surface properties. The value for
the hard surface represents the average of the values obtained for
all hard surfaces measured, including those described with
reference to FIG. 4A. The sensed difference in peak pressure with
different material hardness is a material property or surface
condition that can be used to control the ejection of fluid.
[0081] FIG. 4D is a graph of pressure versus angle of injection
against a hard surface, such as a glass ceramic or steel. The graph
shows that peak pressure varies with the angle of injection, with
the highest pressure measured at an angle of about 90 degrees and
little variation in pressure for angles between about 80 and 0
degrees. The sensed difference in peak pressure with different
ejection angles may be used to control the ejection of fluid.
[0082] Embodiments of the invention may employ a linear
Lorentz-force actuator to propel liquid and/or medicant under
pressure at specific sites along the tissue-tooth interface in
order to expose, identify, and remove plaque from the tooth and
gingival crevice with application to both professional and every
day oral care. Medicant may be any of a number of antiseptics,
anti-plaque agents, or biomarkers that can improve oral hygiene or
aid in the diagnosis of local or systemic disorders.
[0083] In certain embodiments, a Lorentz-force actuator is used to
propel liquid under pressure to the tissue/tooth interface. The
device may be a multi-actuated device that will move along the gum
line with the capability of differentiating between the soft and
hard surfaces comprising the target area. The device may house one
or more Lorentz-force actuators within a hand grip or housing. The
device can be a single or multi actuated device with one or more of
the following properties: [0084] Be contiguous with a tip in fluid
communication with the target (e.g., tissue/tooth interface) and a
small fluid reservoir. [0085] Be in communication with a probe that
can be used to mechanically perturb the tissue/tooth interface and
provide identification of tooth versus tissue within a 2-3 s time
period. In one embodiment, the probe could be attached to a custom
designed linear Lorentz-force actuator and used to apply a force
(<5 N) to the tooth or gum surface (i.e. perturbing the
surface). The tissue responsive to the perturbation can be
displacement analyzed using stochastic system identification as
described in Y. Chen and I. W. Hunter, In vivo characterization of
skin using a Wiener non linear stochastic identification method.
Proceedings of 31.sup.st Annual IEEE Engineering in Medicine and
Biology Conference, (2009) 6010-6013, and in U.S. Pending patent
application Ser. No. 12/872,630, filed on Aug. 31, 2010, entitled
"Nonlinear System Identification Techniques and Device For
Discovering Dynamic And Static Tissue Properties", incorporated by
reference in their entirety. More specifically, the system (i.e.
the actuator, probe tip, and target) is excited using a Gaussian
white noise voltage input which drives the actuator through a
linear power amplifier. The actuator in turn imposes a force on the
probe tip and by extension the target surface. Analysis of the
output (i.e. tissue displacement) permits one to discriminate the
hard tooth surface (high local stiffness) from the soft tissue or
plaque (lower local stiffness). While mechanically attached to the
front of the coil, the probe could maintain some degree of freedom
for repositioning within/between the teeth. In another embodiment
electrical impedance could be used to differentiate between tooth
and gum. [0086] Use one or more strain gauges, attached to the
outer face of the ampoule but well within the volume window, to
determine the deformation of the delivery housing (e.g. ampoule)
with a constant input force (pressure) and variable surface; harder
surfaces (e.g. tooth) exhibiting higher peak pressures than softer
surfaces (e.g. gum). [0087] Use light waves to differentiate
between tooth and gum since the regular structure of tooth ensures
good propagation through the enamel and tubules in the dentin. As
such, changes in structure manifest as changes in scattering of
light as it passes through the tooth and in changes in absorption
and fluorescence on the surface of the tooth. These latter changes
which are normally used to differentiate between healthy and caries
ridden teeth can also be used to differentiate between tooth and
gum. Techniques based on these interactions include, but are not
limited to, multiphoton imaging, infrared thermography, infrared
fluorescence, and optical coherence tomography (OCT). Of these
techniques, OCT is most easily adapted for inclusion into the jet
injection device. [0088] Use an acoustic wave imposed on the fluid
jet together with the actuation of the linear Lorentz-force
actuator to determine the phase difference or time of flight and
force respectively.
[0089] The pressure at which fluid is ejected from the tip is
servo-controlled with delivery of fluid into the fluid reservoir
and ejection through a narrow orifice (i.e. <500 .mu.m) under
pressure to deliver a high jet stream of fluid to the tooth-tissue
interface. The pressure will be varied dependent on the interface.
Prior to delivery the degree of pressure required will be
determined by evaluating the plaque on tooth surfaces and gingiva
using the jet injector.
[0090] In one embodiment, the jet injector is used to deliver
disclosant dyes [D. A. Baab, A. H. Broadwell, and B. L. Williams, A
comparison of antimicrobial activity of four disclosant dyes, J
Dental Res 62 (1983) 837-841] to identify dental plaque. It is
known that there are several dye indicators for dental plaque which
include, but are not limited to, erythrosin (FCD Red #3) (U.S. Pat.
No. 3,309,274), sodium fluorescein (FDC Yellow #8) [in H. Wolf,
Color atlas of dental hygiene: periodontology (2006) 225-227], and
betanin (U.S. Pat. No. 4,431,628).
[0091] In some embodiments, other methods may be used individually
or in combination for plaque identification, including: [0092]
Various optical spectroscopic techniques (e.g. scattering,
absorption, and fluorescence in the visible or infrared) which can
be accomplished by shining a laser beam down the delivery channel
when using a semi transparent jet of liquid. This can also include
OCT technologies. [0093] Raman spectroscopy or faster techniques
such as coherent Raman, Coherent Anti-Stocks Raman Spectroscopy
(CARS) (e.g. broadband, time resolved, frequency-modulated), and
Optical Heterodyned-Detected Raman-Induced Kerr Effect (OHD-RIKE).
These methods may also provide information relating to the
microbial composition based on known or identified Raman spectra
peaks. [0094] Various sound wave technologies (e.g. ultrasound,
elastography), where one can use the phase difference, time of
flight, and reflection response peak intensities to distinguish
plaque from tooth. [0095] Nuclear Magnetic Resonance (NMR).
[0096] The above techniques singly or in combination may be coupled
or combined with stochastic system identification techniques to
determine differences in material properties. The state of the
tooth/tissue interface, as detected by one or more of the above
techniques, can be used to determine, in real time, the waveform
required to mechanically remove plaque from the specific tooth
tissue interface.
[0097] Plaque removal can be accomplished by delivery of a high
pressure jet of fluid, such as water, medicant, or both. Medicant
can include, but is not restricted to, chelating agents, fluoride
(known to inhibit the ability of oral bacteria to create acid) or
fluorescent dyes or probes used to detect bacterial specific
changes (e.g. pH etc.) and/or biochemical specific biomarkers.
Delivery of said medicants may also employ controlled release
packaging such as gel like fluid, particles, or solids. Delivery of
such medicants has been demonstrated by the ability of the ejector
device to deliver colored beads to the subgingival space as
described with reference to FIGS. 5A-5D. Several articles reviewing
potential targets and the use of saliochemistry as a diagnostic
tool have been published [J. K. M. Aps and L. C. Martens, Review:
The physiology of saliva and transfer of drugs into saliva.
Forensic Sci International 150 (2005) 119-131; F. M. L. Amado, R.
M. P. Vitorino, P. M. D. N. Dominigues, M. J. C. Lobo, and J. A. R.
Duarte, Analysis of the human saliva proteome, Exp Rev Proteomics 2
(2005) 521-539; B. J. Baum, A. Voutetakis, and J. Wang, Salivary
glands: novel target sites for gene therapeutics, TRENDS Mol Med 10
(2004) 585-590; E. Kaufman and I. B. Lamster, The diagnostic
applications of saliva-a review, Crit Rev Oral Biol Med 13 (2002)
197-212; A. Aguirre, L. A. Testa-Weintraub, J. A. Banderas, G. G.
Haraszthy, M. S. Reddy, and M. J. Levine, Critical reviews in oral
biology & medicine, Sialochemistry: A diagnostic tool 4 (1993)
343-350].
[0098] FIGS. 5A-5D show the delivery of water and 6 .mu.m beads to
the subgingival space using jet injector 500. Typodont and/or
dentiform tooth and gum models can be used to evaluate the delivery
of black polystyrene beads to the sulcus, which is the natural
space between the tooth and the gum surface. FIG. 5A shows typodont
501, which is a model of the oral cavity, including teeth 502,
gingival 504, and the palate (not shown). The typodont 501 can
include polymers of different stiffness for the gingiva, or gums,
504. FIG. 5A shows the delivery of water 512 to the tooth/gum
interface of typodont model 501 using the jet injector 500. Only
part of the jet injector, the distal end of the ampoule or
reservoir, is visible. FIG. 5B shows the delivery beads 514 and
water to the tooth/gum interface of the typodont model 501 using
the jet injector. The delivery waveform was tailored to eject a
solution of beads at 100 m/s for 10 seconds in order to separate
the tooth and gum followed by delivery of the remaining solution at
10 m/s in order to deposit bead into the sulcus. FIG. 5C shows the
typodont model 501 after delivery of beads to the gum line 506
using the jet injector. FIG. 5D shows the typodont model of FIG. 5C
with the gum 504 partly pulled away by probe 510 to expose the
beads delivered to the sulcus 508. Delivery of beads to the sulcus
demonstrates the use of the jet injector, such as device 200 of
FIG. 2A, for delivery of medicant to this area.
[0099] In some embodiments, identification and/or removal of plaque
may be coupled with oral diagnostics, including, for example,
detection or change in concentration of an analyte (e.g. antigen,
antibody, nucleic acid etc.) in a fluid. The jet injector may be
used to remove a small volume of saliva either pre- or
post-brushing/cleaning to evaluate oral health and/or systemic
health.
[0100] In one embodiment, the jet injector can be used to remove a
small amount of fluid that would be mixed with a conjugated
antibody (fluorescent, enzymatic etc.), and loaded into a
microtiter plate, the wells of which contain antibody to the
antigen(s) of interest. Binding would be detected by addition of an
appropriate substrate.
[0101] In another embodiment, saliva may be collected into a
modified, disposable tip lined with a solid support or matrix
containing an antibody array. Detection would involve inclusion of
a second, specific labeled antibody or enzyme-antibody conjugate
with subsequent substrate. Unbound analyte and binding reagent
would be removed by delivery and removal of a wash solution after
each binding reaction using the bi-directionality of the linear
Lorentz-force actuator.
[0102] FIG. 6 shows an exemplary device 600 for detecting an
analyte from a sample collected in a disposable tube. The device
uses a disposable, spherical tube (e.g. straw) 602 for the
collection of saliva. After collection, the tube is placed within a
non-disposable detector or analyzer 604. In one embodiment, fluid,
such as saliva, may be deposited or drawn directly into a
disposable, spherical tube 602, using the jet injector device,
reacted with specific, labeled or conjugated binding reagent (e.g.
fluorophore or enzymatic respectively) dried onto the inner surface
of the straw at a specific location, and then absorbed onto a solid
support or matrix, for example a polymer, containing one or more
antibodies of interest bound at a specific site. At this point, the
straw 602, if still attached to the jet injector device, can be
removed and slid into the non-disposable detector 604. Unbound
analyte and binding reagent may be removed by passage of a wash
solution through the straw followed by substrate if using an enzyme
conjugate. The device 600 may include user controls, such as power
button 606, to start and control the analysis and measurement. A
display 608 may also be included to display the results of the
measurement to the user. Detector or analyzer 604 may, for example,
include detector 1000 described with reference to FIG. 10.
[0103] In some embodiments, a detector or analyzer, such as
detector 600, may be integrated into the jet injector. As shown in
FIG. 1, optional detector or analyzer 122 may be coupled to or
included in the needle-free injector 100 to detect a marker of oral
health using the analyzer 122. The injector 100 may control
ejection of a substance against tooth or gum responsive to the
detected marker. In one embodiment, the jet injector uses a
Lorentz-force actuator to eject the substance, which may be fluid
or a fluid containing a medicant. Because the Lorentz-force
actuator is bi-directional, depending upon the direction of the
coil current, the same device used to inject a substance can also
be used to withdraw a sample. This is a beneficial feature as it
enables the device to collect a sample.
[0104] Referring to FIG. 7A, an exemplary sampling, needle-free
injector 700 is illustrated. The sampling jet injection device 700
includes a bi-directional electromagnetic actuator 702 abutting at
one end a first piston 714A. A sampling nozzle 711A is coupled at
the other end of a syringe or ampoule 710. The actuator 702 is
controlled by controller 704. Controller may include a power source
(not shown), such as a battery or suitably charged storage
capacitor, to power the actuator 702. The first piston 714A is
slidably disposed within a sampling syringe 710, such that an
electrical input signal applied to the actuator 702 withdraws the
first piston 714A away from the sampling nozzle 711A. A sample can
be collected from an oral cavity or a surface when the sampling
nozzle 711A is placed in the oral cavity or near the surface during
actuation. Collecting a sample may include first ejecting a
substance into the oral cavity or against a surface and then
withdrawing a sample that includes at portion of the ejected
substance and a biological sample, e.g., a biological fluid.
[0105] Referring now to FIG. 7B, once a sample has been collected,
a movable syringe mount 708 can be re-positioned such that the
sampling syringe 710 is aligned with an analyzer or detector 706.
By the same motion, a second syringe 712 having a second piston
714B and including a substance, such as a fluid, cleansing agent,
or medicant, is aligned with the actuator 702. The mount 708 may be
a rotary mount rotating about a longitudinal axis or a linear mount
as shown. The analyzer or detector 706 provides a control signal to
the controller 704 responsive to the analyzed sample. The control
signal, via controller 704, causes the actuator 702 to push the
second piston 714B forward thereby expelling an amount of the
substance responsive to the analyzed sample. Thus, the same device
700 can be used to both collect a sample and to eject a substance.
In an embodiment, the jet injector device may include two jet
injectors and/or actuators, one to sample and the other to eject a
substance responsive to the analyzed sample.
[0106] In yet another embodiment, a polymer strip containing
plaque-specific biomarkers, for example Streptococcus species, is
attached to a disposable head of a tooth brush or tooth brush-like
device. FIG. 8 shows an example of a disposable, polymer strip 802
containing a plaque-specific biomarker attached to the head of a
toothbrush or toothbrush-like device 800. The strip 802 can be
attached to or included in a disposable top section 810 or device
800. The strip 802 may be coupled to or in fluid communication with
a sensor section 804 of device 800 via top section 810. When
inserted into the mouth, the polymer strip will absorb saliva and
bind analyte(s) of interest. The strip can then be peeled away and
processed as above or the strip can be analyzed by sensor 804 on
the device itself. For example, binding of an analyte of interest,
such as a plaque-specific biomarker, can be determined by a change
in impedance. Binding of an analyte can also be determined by a
change in absorbance or fluorescence, as for example by enzyme
linked immunoabsorbant assay (ELISA). The device can include a
power and measurement button 806 to initiate the analysis. A
display 808 may be included to display results of the analysis to a
user.
[0107] The above embodiments may be configured or modified to
detect changes in antibody concentration, for example IgA, a common
component of the mucosal immune system. In this case, the analyte
would bind to a specific antigen with detection by a labeled
secondary antibody, as for example described below with reference
to FIGS. 9A-9B and FIG. 10.
[0108] FIGS. 9A-9B illustrate the use of disposable, polymeric
strips to evaluate oral health status. FIG. 9A is schematic diagram
showing binding of an analyte 904 (in this case antibody) to a
solid support 900 (in this case a polypyrrole film strip) to which
antigen 902, specific to the analyte of interest, can be adsorbed,
entrapped, or covalently attached. Prior to the addition of
analyte, unbound antigen is removed by washing and free sites on
the polymer strip blocked to prevent non-specific binding of
successive reagents. Addition of analyte 906 followed by washing
and blocking prior to the addition of labeled secondary antibody
specific to the analyte. The secondary antibody may be conjugated
to a fluorophore or enzyme, for example horseradish peroxidase
(HRP) 908 as shown. In this latter case, binding is detected by the
addition of a substrate 910 that, in the presence of HRP, yields a
colored product that can be detected by reading absorbance.
Alternatively, binding of primary antibody could be detected by
measuring a change in electrical impedance. FIG. 9B is a plot of
ELISA results showing increase in absorbance observed with
absorption of increasing concentrations of antigen into polypyrrole
film strips.
[0109] FIG. 10 is a schematic diagram showing a detector for
detecting a marker or analyte of oral health status, such as a
labeled or conjugated antibody shown in FIG. 9A. The detector 1000
consists of a light source 1002 that excites the sample 1004 with
light 1003, and photodiode 1006 to measure the light emitted from
the sample. Sample 1004 includes the marker or analyte of interest.
Detector 1000 further includes a lens 1008 to focus the light of
the light source 1002 on the sample 1004, and a dichroic mirror
1010 to reflect the light emitted from the sample through a second
lens 1009 and into the photodiode 1006. Light source 1002 may
include a light-emitting diode (LED). Sample 1004 may be supported
by or deposited on a solid support 1012, which may include a
polymer strip, such as strip 900 described with reference to FIG.
9A.
[0110] Alternatively or in addition to optical detection, binding
of a marker or analyte may also be detected using electrical
impedance. Furthermore, saliva samples obtained using the jet
injector could be processed directly using Coherent Raman
spectroscopy.
[0111] The devices and techniques described herein provide a means
of quantifying specific bacterium, antibody, etc. relevant to oral
health and disease and thereby a means of determining effective and
appropriate intervention strategies.
[0112] The teachings of all patents, published applications and
references cited herein are incorporated by reference in their
entirety.
[0113] While this invention has been particularly shown and
described with references to example embodiments thereof, it will
be understood by those skilled in the art that various changes in
form and details may be made therein without departing from the
scope of the invention encompassed by the appended claims.
* * * * *